<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Document</title>
  </head>
  <body>
    <script>
      var name = '222'
      var a = {
        name: '111',
        say: function() {
          console.log(this.name)
        }
      }
      var fun = a.say
      fun() // 222
      a.say() // 111

      var b = {
        name: '333',
        say: function(func) {
          func()
        }
      }

      b.say(a.say) // 222
      b.say = a.say
      b.say() // 333
    </script>
  </body>
</html>
